Hydrogenated alkyl aromatics as petroleum distillate fuel cold flow improvers

ABSTRACT

Hydrogenated alkyl aromatics are useful as petroleum oil additives such as wax crystal modifiers and cold flow improvers for petroleum oils, e.g. atmospheric distillate fuels, particularly when used in combination with ethylene backbone middle distillate pour point depressants such as branched polyethylene, copolymers of 4 to 30 molar proportions of ethylene with an unsaturated ester, e.g. vinyl acetate, or another olefin, etc.

United States Patent Feldman et al.

[451 May 13, 1975 [75] Inventors: Nicholas Feldman, Woodbridge;

Stephan Ilnyckyj, Maplewood, both of NJ.

[73] Assignee: Exxon Research and Engineering Company, Linden, NJ.

[22] Filed: Aug. 24, 1972 [21] Appl. No.: 283,388

[52] U.S. Cl. 44/62; 44/66; 44/80; 252/78 [51] Int. Cl C101 1/20 [58] Field of Search 44/62, 80, 66; 208/33 [56] References Cited UNITED STATES PATENTS 2,246,311 6/1941 Lieber et al. 252/59 2,798,027 7/1957 Cohen 208/38 2,906,688 9/1959 Farmer et a1. 208/33 3,108,944 10/1963 7 Stoller 208/33 3,250,599 5/1966 Kirk et a1 44/62 3,262,873 7/1966 Tiedje et a1 208/33 3,475,321 10/1969 l-Ienselman et a1. 44/62 3,523,073 8/1970 Moyer 208/33 3,639,226 2/1972 Henselman et a1. 208/33 FOREIGN PATENTS OR APPLICATIONS 1,154,966 6/1969 United Kingdom 44/62 Primary ExaminerDaniel E. Wyman Assistant Examiner-Y. H. Smith Attorney, Agent, or Firm-Frank T. Johmann [57] ABSTRACT Hydrogenated alkyl aromatics are useful as petroleum oil additives such as wax crystal modifiers and cold flow improvers for petroleum oils, e.g. atmospheric distillate fuels, particularly when used in combination with ethylene backbone middle distillate pour point depressants such as branched polyethylene, copolymers of 4 to 30 molar proportions of ethylene with an unsaturated ester, e.g. vinyl acetate, or another olefin, etc.

10 Claims, No Drawings HYDROGENATED ALKYL AROMATICS AS PETROLEUM DISTILLATE FUEL COLD FLOW IMPROVERS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to hydrogenated alkyl aromatics and their use for improving the cold flow properties of petroleum oils, particularly distillate fuel oils.

2. Description of the Prior Art Kerosene, which is a solvent for wax, had traditionally been a component of distillate fuel oils, e.g. diesel fuels, home heating oils, etc. With the demands for kerosene for use in jet fuels, the amount of kerosene used in middle and heavy distillate fuel oils have decreased over the years. This, in turn, has frequently required the addition of wax crystal modifiers, e.g. pour point depressant additives, to the fuel oil to make up the lack of kerosene.

One class of such pour point depressant additives are alkylated aromatics, particularly the wax-naphthalene pour depressants. These materials have been used in various petroleum oils, such as lubricating oils, e.g. see U.S. Pat. Nos. 1,815,022 and 2,297,292; as dewaxing aids, including use with other co-additives, e.g. see U.S. Pat. Nos. 3,417,010 and 3,475,321; and as pour depressants for middle distillate fuels, e.g. see U.S. Pat. No. 3,245,366.

Another class of material containing various alkyl aromatics are certain classes of petroleum wax such as the substantially paraffin-free petrolatum described in U.S. Ser. Nos. 807,965 and 807,966 by Nicholas Feldman and U.S. Pat. No. 3,660,057 by Stephan llnyckyj.

Alkyl aromatics are also present in the more common paraffin-containing microcrystalline waxes. Use of such various microcrystalline waxes as wax-crystal modifiers for fuels, in conjunction with the polymeric ethylene containing pour point depressants, is known in the art, and is described for example in U.S. Pat. No. 3,250,599 which teaches copolymers of ethylene and vinyl fatty acids, e.g. vinyl acetate, with a petroleum microcrystalline wax. A related patent U.S. Pat. No. 3,288,577 teaches a petroleum microcrystalline wax used with copolymers of ethylene and vinyl fatty acid esters, or copolymers of styrene and C to C alpha olefin, or the condensation product of an aromatic hydrocarbon with a polyunsaturated ester by means of a Friedel-Crafts reaction. U.S. Pat. No. 3,445,205 teaches microcrystalline wax with a polymer of acrylic acid ester in fuels.

Ethylene polymeric pour point depressants for middle distillate fuels are well known. Examples include copolymers of ethylene with various other monomers, e.g. copolymers of ethylene and vinyl esters of lower fatty acids such as vinyl acetate (U.S. Pat. No. 3,048,479); copolymers of ethylene and alkyl acrylate (Canadian Pat. No. 676,875); terpolymers of ethylene with vinyl esters and alkyl fumarates (U.S. Pat. Nos. 3,304,261 and 3,341,309); polymers of ethylene with other lower olefins, or homopolymers of ethylene (British Pat. Nos. 848,777 and 993,744); chlorinated polyethylene (Belgium Pat. No. 707,371) etc.

SUMMARY OF THE INVENTION The present invention is based upon finding that by hydrogenating alkyl aromatics, e.g. the aforesaid waxnaphthalene pour point depressants or the alkyl aromatics contained in the aforedescribed petrolata, that their effectiveness can be increased and they are then particularly useful in atmospheric distillate fuel oils for controlling wax crystal size and improving cold flow of the oil.

Thus, many of the aforedescribed prior art materials, e.g. the aforesaid ethylene backbone pour point depressants, which have achieved widespread commercial use, while very effective in lowering the pour point of distillate fuel oil, sometimes do not sufficiently reduce the particle size of the wax crystals that form. These large wax particles tend to be filtered out by the screens and other filter equipment normally used on delivery trucks, fuel oil storage systems, etc. with a resulting plugging of these screens and filters even though the temperature of the oil is substantially above its pour point. In general, one advantage of the hydrogenated material, particularly when used with one of said ethylene backbone materials, is that it can frequently control the wax crystal size to obtain very small crystals which will pass through said screens and filters.

Because of this increased effectiveness in regulating wax crystal size, the additives of the invention are particularly useful in diesel fuels in view of the current tendency and desire to increase the maximum distillation point of diesel fuels. One advantage of increasing said maximum distillation is that the resulting fuel will then contain a larger proportion of higher molecular weight hydrocarbons, which in turn, increases the BTU value of the fuel. This greater BTU value give economies during the operation of diesel engines, for example, diesel trucks. However, raising the maximum distillation point will raise the pour point and the cloud point. Thus, current diesel fuels usually have pour points on the order of -20F. By increasing the distillation temperature, the diesel fuels can have pour points as high as +5 or +10F., or higher. Correspondingly, the cloud point is also increased. Thus, the cloud point is usually a few degrees (e.g. 3l5F.) higher than the pour point, although in some fuels, the cloud point may be as much as 25F. above the pour point. The higher pour point, in turn, brings about a requirement for reduction of pour point which can be accomplished by the addition of pour point depressants. The higher cloud point will usually mean that the wax crystals become more of a problem so that the wax crystal size will frequently need to be controlled. For example, in the normal operation of diesel trucks, the diesel engine is usually provided with a fine mesh filter of about 50 microns, e.g. about equivalent to a 270 mesh screen, ahead of the engine. In cold weather when the ambient temperature is below the cloud point, any wax crystals that form should be sufficiently fine so that they will pass through these filters.

Compositions of the invention will comprise a major amount of petroleum oil, e.g. lubricating oil, residua fuel oil, etc., but preferably an atmospheric distillate fuel, improved in flow characteristics by a minor, flow improving amount of hydrogenated alkyl aromatic. These distillate fuel compositions can also contain an ethylene polymeric pour point depressant, usually in relative ratios of 0.1 to 25, preferably 0.5 to 10 parts by weight of the hydrogenated alkyl aromatic per part by weight of the ethylene polymer.

The Distillate Fuels Broadly speaking, the distillate fuel oils will boil in the range of 250 to 1,200F., e.g. 250 to 900F. The

middle distillate fuels usually have boiling ranges in the range of about 250F. to about 700F. while heavy distillate fuels may have a major amount of the fuel boiling in the 250 to 700F. range but with a minor amount and a final boiling point (FBP) in the range of 700 to 1,200F., e.g. 700 to 900F. The fuel oil can comprise straight run or cracked gas oil or a blend in any proportion of straight run and thermally and/or catalytically cracked distillates, or blend of middle distillates and heavy distillates, etc. The most common petroleum middle distillate fuels are kerosene, diesel fuels, jet fuels and heating oils. Heavy distillate fuels are usually marine diesel fuels and heavy turbine fuels. The low temperatureflow problem is most usually encountered with diesel fuels and with heating oils.

A typical heating oil specification calls for a percent distillation point no higher than about 440F., a 50 percent point no higher than about 520F., and a 90 percent point of at least 540F. and no higher than The Alkyl Aromatics These materials, e.g. wax-aromatics condensates, are

usually made by the Friedel-Crafts condensation of a ing a melting point within the range of about 100 to 20091 The aromatic hydrocarbon used usually contains a maximum of three substituent groups and/or condensed rings and may be a hydroxy compound such as phenol, cresol, xylenol, or an amine such as aniline,

but is preferably naphthalene, phenanthrene or anthracene.

Another source of alkyl aromatics as indicated above are certain petrolatums (which may be microcrystalline, or may be generally amorphous solid materials) having melting points within the range of about 80 to 200F. or higher, and number average molecular weights within the range of about 500 to about 3,000, e.g. 600 to 2,500, preferably 600 to 1,500. These molecular weights are above those of compounds normally present in middle distillate fuels which on the average are about 240 and seldom as high as 400.

The petroleum microcrystalline wax includes those hydrocarbon waxes which are normally derived from heavy lubricating oil fractions obtained from paraffin and mixed base crude oils and which waxes have a fine, less apparently crystalline structure than paraffin wax. The wax can contain up to 40% oil, more often about 5 to 25 wt. or the wax may be in the more refined or deoiled form. In the derivation of the microcrystalline waxes the heavy lubricating oil stocks, e.g. residual stocks, may first be subjected to solvent deasphalting, solvent refining with phenol or other solvents selective for aromatics or hydrotreating, and then to the normal dewaxing and deoiling procedures to produce the wax. Dewaxing may be accomplished by any one of a number of suitable processes including solvent extraction at low temperatures followed by crystallization and separation by centrifugation or by solvent dewaxing with methylethylketone solutions, etc. The resulting petrolatum wax may, if desired, be further deoiled as by methylethylketone treatment to give a variety of microcrystalline waxes. The wax may also be obtained as foots waxes or foots oils during the manufacture of other microcrystalline waxes.

While microcrystalline waxes may be used, preferred waxy materials, because of general increased effectiveness, are amorphous solid materials, essentially free of normal paraffinic hydrocarbons, i.e. they will normally contain less than 5 wt. of normal paraffin, preferably less than about 1 wt. of normal paraffin hydrocarbons.

These amorphous hydrocarbon fractions can be obtained by deasphalting a residual oil fraction, then adding a solvent to the deasphalted residuum, lowering the temperature of the solvent-diluted residuum, and recovering the desired solid or semi-solid material by precipitation at a low temperature, followed by filtration. Said residual oil fraction will usually have a viscosity of at least 125 SUS. at 210F., and commonly will be a bright stock. In some instances products obtained by this procedure will be naturally low in normal paraffin hydrocarbons depending on the crude source. For example, by low temperature propane treatment of a deasphaited residual oil from certain Texas coastal crudes, a precipitated high molecular weight amorphous fraction can be obtained which has only a trace of normal paraffins, about 5% of isoparaffins, about 73% of cycloparaffins and about 22% of aromatic hydrocarbons.

In the following working examples, WAX A that was used was such an amorphous solid hydrocarbon fraction having a melting point of 1 10F., obtained by propane precipitation from a deasphalted residual stock from a Texas coastal crude oil. This hydrocarbon fraction was found by mass spectrographic analysis and gas chromatography tocontain about 5 wt. of isoparaffins, 22 wt. of aromatic hydrocarbons, 73 wt. of cycloparaffins, and no more than a trace of normal paraffins. The number average molecular weight of this material was about 775 as determined by Vapor Pressure Osmometry, (VPO). The distillation characteristics of this solid amorphous hydrocarbon fraction were as follows:

Only 24 percent would distill over. There were 75 percent bottoms, and 1 percent loss.

These petrolatums can be hydrogenated per se to thereby hydrogenate their alkyl aromatic portion. Alternatively, the alkyl aromatic portion can be first separated from the wax and then hydrogenated.

For example, WAX A described above can be separated by conventional techniques into an aromatic hydrocarbon fraction (22%) and a non-aromatic hydrocarbon fraction (78%), e.g. by a silica gel separation technique wherein the original wax, e.g. WAX A, is dissolved in 5 to 25 parts by weight of normal heptane per part by weight of wax. The resulting solution is percolated through a column of silica gel, the column is then flushed with 100 to 500 parts by weight of normal heptane to remove non-aromatics. The aromatics that had been adsorbed in the column are then recovered by washing the column with 50 to 500 parts of acetone and then evaporating the acetone from the recovered material to obtain the alkyl aromatic fraction.

Conditions of Hydrogenation The hydrogenation of the alkyl aromatics is carried out using conventional hydrogenation procedures. The alkyl aromatic is preferably diluted with inert solvent, usually a hydrocarbon such as heptane, cyclohexane, aliphatic naphtha, etc., and along with hydrogenation catalyst, is added to a high pressure autoclave, pressured with hydrogen to about 500 to 10,000 psig., preferably 2000 to 4000 psig., and then heated to 230 to 400C., preferably 300 to 370C, for about 1 to 24, e.g. 2 to hours, while stirring. Hydrogen is preferably supplied during the reaction through a pressure regulating valve to maintain the desired pressure. When hydrogenation is completed, the reactor is depressurized, the catalyst removed by filtering, and the hydrogenated alkyl aromatic recovered from the solvent simply by evaporation of the solvent.

The hydrogenation catalyst will generally be used in amounts of 0.1 to wt. e.g. S to 10 wt. based upon the weight of the alkyl aromatic to be hydrogenated and depending upon the specific catalyst used. In the absence of sulfur compounds, useful catalyst include the common hydrogenation catalysts such as: Raney nickel, platinum oxide, platinum on alumina, palladium on charcoal, copper chromate, nickel supported on kieselguhr, molybdenum sulfide and the like. If sulfur is present as impurities, then cobalt molybdate or nickel tungstate are preferred catalysts as they are resistant to sulfur poisoning.

The Ethylene Backbone Pour Depressant 1n general, these polymeric pour depressants have a polyethylene backbone which is divided into segments by hydrocarbon or oxy-hydrocarbon side chains. Generally, they will comprise about 3 to 40, preferably 4 to 20, molar proportions of ethylene per molar proportion of a second ethylenically unsaturated monomer, which latter monomer can be a single monomer or a mixture of such monomers in any proportion. These oil-soluble polymers will generally have a number average molecular weight in the range of about 500 to 50,000, preferably about 1,000 to about 5,000, as measured for example, by Vapor Pressure Osmometer, such as using a Mechrolab Vapor Pressure Osmometer Model 310A.

The unsaturated monomers, copolymerizable with ethylene, include unsaturated mono and diesters of the general formula:

wherein R, is hydrogen or methyl; R is a -OOCR., or -COOR, group wherein R, is hydrogen or a C, to C,,,, preferably a C, to C straight or branched chain alkyl group; and R is hydrogen or -COOR,. The monomer, when R, and R are hydrogen and R is OOCR, includes vinyl alcohol esters of C to C monocarboxylic acids, preferably C to C monocarboxylic acid. Examples of such esters include vinyl acetate, vinyl isobutyrate, vinyl laurate, vinyl myristate, vinyl palmitate, etc. When R is COOR,, such esters include methyl acrylate, isobutyl 'acrylate, methyl methacrylate, lauryl acrylate, C Oxo alcohol esters of methacrylic acid. etc. Examples of monomers where R, is hydrogen and R and R are COOR,, groups, include mono and diesters of unsaturated dicarboxylic acids such as: mono C,,, Oxo fumarate, di-C Oxo fumarate, di-isopropyl maleate; di-lauryl fumarate; ethylmethyl fumarate; etc.

Another class of monomers that can be copolymerized with ethylene include C to C,,, alpha monoolefins, which can be either branched or unbranched, such as propylene, isobutene, n-octene-l, isooctene-l, ndecene-l, dodecene-l, etc.

Still other monomers include vinyl chloride, although essentially the same result can be obtained by chlorinated polyethylene. Or even branched polyethylene can be used per se as the pour depressant.

These polymeric pour depressants are generally formed using a free radical promoter, or in some cases they can be formed by thermal polymerization, or they can be formed by Ziegler type polymerization in the case of ethylene with other olefins. The polymers produced by free radical appear to be the more important and can be formed as follows: Solvent, and 0-50 wt. of the total amount of monomer other than ethylene, e.g. an ester monomer, used in the batch, are charged to a stainless steel pressure vessel which is equipped with a stirrer and cooling coil. The temperature of the pressure vessel is then brought to the desired reaction temperature, e.g. to 250C, and pressured to the desired pressure with ethylene, e.g. 800 to 10,000 psig., usually 900 to 6,000 psig. Then promoter, usually d1 luted with the reaction solvent, and additional amounts of the second monomer, e.g. unsaturated ester, are added to the vessel continuously, or at least intermittently, during the reaction time, which continuous addition gives a more homogeneous copolymer product as compared to adding all the unsaturated ester at the beginning of the reaction. Also during this reaction time, as ethylene is consumed in the polymerization reaction, additional ethylene is supplied through a pressure controlling regulator so as to maintain the desired reaction pressure fairly constant at all times. Following the completion of the reaction, usually a total reaction time of 1 1 to 10 hours will suffice, the liquid products are withdrawn from the pressure vessel, and the solvent removed by stripping, leaving the polymer as residue. Usually, to facilitate handling and later blending into oil, the polymer is dissolved in a light mineral oil to form a concentrate usually containing 10 to 60 wt. polymer.

Generally, based upon 100 parts by weight of copolymer to be produced, then about 50 to 1220, preferably 100 to 600, parts by weight of solvent, e.g. hydrocarbons such as benzene, hexane, cyclohexane, etc., and about 0.1 to 20, e.g. 1 to 5, parts by weight of promoter will be used.

The promoter can be any of the conventional free radical promoters, such as peroxide or-azo-type compounds, including the acyl peroxides of C to C branched or unbranched carboxylic acids, alkyl peroxides, etc. including di-benzoyl peroxide, ditertiary butyl peroxide, di-tertiary butyl perbenzoate, tertiary butyl hydroperoxide, alpha, alpha, azo-diisobutyronitrile, dilauroyl peroxide, etc.

The oil compositions of the invention will generally comprise a major amount of the oil, e.g. distillate fuel oil, and about 0.01 to 3 wt. preferably 0.05 to 0.5 wt. of the hydrogenated alkyl aromatic. In addition, the composition can also contain about 0.001 to 2 wt. preferably 0.005 to 0.15 wt. of the aforedescribed ethylene backbone pour point depressant. Oil concentrate of 3 to 60 wt. of said hydrogenated material, with or without said ethylene material, e.g. in a distillate fuel oil, can be prepared for ease in handling. Said weight percents are based on the weight of the total composition.

The invention will be further understood by reference to the following Examples which include preferred embodiments of the invention and wherein the following materials were used:

Hydrogenated Wax-Naphthalene Wax-naphthalene made from 100 parts by weight of about 128F. melting point n-paraffin wax chlorinated to 12 wt. chlorine condensed with 14 parts naphthalene (Friedel-Crafts condensation) was hydrogenated as follows:

10 grams of the wax-naphthalene, 0.2 grams of carbon disulfide to keep the catalyst sulfated, hydrogenation catalyst consisting of 10 grams of sulfated Nalco- 471 and 10 grams of sulfated Nalco NT-550, were charged to a pressure vessel and heated with stirring to temperatures of about 350C. for about 6 hours. About 17 grams of hydrogenated product was recovered by filtering out the catalyst and stripping of the solvent. The Nalco-471 was a cobalt (3.5%) molybdate (12.5%) on alumina. The Nalco NT-550 was nickel (4%) tungstate (16%) on alumina.

Hydrogenated Alkyl Aromatics from Petrolatum The Aromatic Fraction of the aforedescribed WAX A was extracted as follows:

100 grams of WAX A was dissolved in 500 ml. normal heptane and the resulting solution was percolated through a glass column 8 feet long and 2 inches diameter filled with 60/100 mesh silica gel (Davidson).

The saturated portion of the petrolatum was eluted from the column with n-heptane until pure solvent came through. The aromatics that had been adsorbed in the column were then recovered by washing the column with about liters of acetone and then removing the acetone from the resulting solution. 22 gm. of Aromatic Fraction were thereby obtained.

The Aromatic Fraction was analyzed by mass spectroscopy and found to contain 22.7 wt. of one ring alkyl aromatics, the balance being multi-ring compounds.

A portion of the aforedescribed Aromatic Fraction was hydrogenated as follows:

10 gm. of the Aromatic Fraction, 0.2 gm. of carbon disulfide, 10 gm. of Nalco-471 and 10 gm. of Nalco- 550 were placed in an autoclave which was then pressurized with hydrogen to 3,000 psig and heated to 350C. for 6 hours. Upon the completion of the reaction, the solvent and the catalyst were removed, leaving about 9 grams of product.

Ethylene Backbone Polymer Copolymer A was an ethylene-vinyl acetate random copolymer having a number average molecular weight of about 1900 as determined by Vapor Phase Osmometry, having about 1.5 methyl terminated branches (exclusive of the methyl groups in the vinyl acetate) per 1,000 molecular weight of polymer, and about 38 wt. vinyl acetate. The copolymer was prepared by copolymerizing ethylene and vinyl acetate with dilauroyl peroxide at a temperature of about 105C., under about 1050 psig ethylene pressure in cyclohexane solvent. A typical laboratory preparation of this polymer is as follows:

A three liter stirred autoclave is charged with about 1000 ml. of cyclohexane as solvent and about ml. of vinyl acetate. The autoclave is then purged with nitrogen and then with ethylene. The autoclave is then heated to C. while ethylene is pressured into the autoclave until the pressure is raised to about 1050 psig. Then, while maintaining a temperature of 105C. and said 1050 psig. pressure, about ml/hour of vinyl acetate and about 80 ml/hour of solution consisting of 9 wt. di-lauroyl peroxide dissolved in 91 wt. cyclohexane is continuously pumped into the autoclave at an even rate. A total of 320 ml. of vinyl acetate and 1 1 gm. of peroxide are injected into the reactor over a period of about 2 hours. After the last of said peroxide is injected, the batch is maintained at 105C. for an additional 10 minutes. Then, the temperature of the reactor contents is lowered to about 60C., the reactor is depressurized, and the contents are discharged from the autoclave. The empty reactor is rinsed with 1 liter of warm benzene (about 50C.) which is added to the product. The product is then stripped of the solvent and unreacted monomers on a steam bath overnight by blowing nitrogen through the product.

Further examples of this class of polymer is described in Canadian Pat. No. 882,194. Details of measuring the branching of this type of polymer are given in Journal of Applied Polymer Science, Vol. 15, pp. 1737-1742 (1971 Copolymer B was an ethylene-vinyl acetate random copolymer having a number average molecular weight (VPO) of about 4100, containing about 9 wt. vinyl acetate, and a specific viscosity, measured in 1 wt. solution in toluene at 100F., of about 0.37.

Fuels Fuel A was diesel fuel having +8F. ASTM cloud point, boiling in the range of about 346 to 647F. (ASTM-D86), and having an aniline point of 143F.

Fuel B was a diesel fuel having a +7F. ASTM cloud point, a boiling range of 389 to 643F. (ASTM-D86), and having an aniline point of 137F.

Fuel C was a diesel fuel having a +40F. ASTM cloud point, an aniline point of F., and having the following distillation (ASTM D-1160) characteristics:

The following flow tests were used to measure the cold flow characteristics of the waxy fuels.

Flow Test A In this test a 200 ml. sample of oil is coo1ed at a rate of 4F./hr. from 10F. above the cloud point of the oil to -5 or lF., at which temperature the oil is allowed to pass under 36 inches of water vacuum through a 270 mesh screen of 1 cm. diameter. The percent of the sample that passes through in 25 seconds is reported.

Flow Test A This test is carried out in the general manner as Flow Test A except that the finest mesh screen that the oil will pass through in 25 seconds at -F. is reported.

Flow Test B This test is carried out by the procedure described in Journal of the Institute of Petroleum," Volume 52, No. 510, June 1966, pp. 173-185. The test is carried out with a 45 ml. sample of the oil in an ASTM cloud point jar cooled in a bath maintained at about 30F. Every two degrees drop in temperature, starting from 4F. above the cloud point, the oil is forced under a suction of 8 inches of water through a filter element provided with a 350 mesh screen into a pipette to a mark indicating a volume of ml., at which time the oil is allowed to return by gravity flow to the cooling chamber. The test is repeated with each two degrees drop in oil temperature until the oil fails to fill the pipette in a period of 60 seconds to the aforesaid mark. The results of the test are reported as the highest temperature at which the oil fails to fill the pipette.

Blends of the above described materials in the various aforesaid fuels were made up and tested according to said Flow Tests. The results obtained are summarized in the following tables.

TABLE II Flow Test A Recovery Additive in Fuel B at -10F.

.135 wt. Copolymer A l .045 wt. 71 Copolymer A 0 0.4 wt. 71 Aromatic Fraction .045 wt. "/1 Copolymer A 100 .471 Hydrogenated Aromatic Fraction None 0 TABLE 111 Flow Test A. Flow Additive in Fuel C mesh passed Test B.F.

,0225 wt. Copolymer B 100 26 .0225 wt. Hydrogenated 100 30 Wax Naphthalene .01 12 wt. Hydrogenated Wax Naphthalene 100 20 .01 12 wt. Copolymer B None 34 As seen by Table I, the wax-naphthalene and the ethylene-vinyl acetate (Copolymer A) pour point depressant per se were ineffective in 0.045 wt. concentrations in Fuel A at 5F. and -l0F. in Flow Test A. By increasing the amount of wax-naphthalene from 0.045 to 0.135 wt. 100% passage was obtained at -5F., and 60% passage was obtained at -l0F., of said 200 ml. sample. By further increasing the amount of wax-naphthalene and Copolymer A the percent passage at -l0F. was raised to However, the last combination of Table 1, wherein 0.045% of the hydrogenated wax-naphthalene was used with 0.045 wt. of Copolymer A gave passage at both the 5 and 10F. temperature, thus illustrating the improved results obtained by the hydrogenation. In Table 11, use of the aforesaid Aromatic Fraction with Copolymer A in Fuel B did not pass the flow test at l0 F., although the hydrogenated Aromatic Fraction gave a 100% passage, thus again demonstrating the increased effectiveness in controlling the wax crystal size that occurs upon hydrogenating the alkyl aromatic. Table 111 shows that the hydrogenated wax-naphthalene per se was effective in controlling the wax crystal size, and the combination of hydrogenated wax-naphthalene and Copolymer B was even more effective, as measured by Flow Test B, which gives the highest temperature that plugging of the screen occurs.

What is claimed is:

1. A distillate petroleum fuel oil having at least a major proportion boiling in the range of about 250 to 700F., improved in its flow properties by 0.01 to 3 wt. of a flow improving hydrogenated alkyl aromatic fraction of an amorphous normally solid wax having a melting point in the range of about 80 to 200F. and a molecular weight in the range of about 600 to about 3,000 obtained from a residual petroleum oil.

2. A distillate petroleum fuel oil having at least a major proportion boiling in the range of about 250 to 1 l 700F., improved in its flow properties by containing in the range of about 0.01 to 3 wt. of a hydrogenated alkyl aromatic selected from the group consisting of:

a. hydrogenated wax aromatic pour point depressant which is the Friedel-Crafts condensation product of wax having a melting point of about 100 to 200F. chlorinated to about 5 to 25 wt. chlorine and condensed with an aromatic in a relative weight ratio of about 5 to parts of chlorinated wax per part of said aromatic, and b. a hydrogenated alkyl aromatic fraction of an amorphous normally solid wax having a melting point in the range of about 80 to 200F. and a molecular weight in the range of about 600 to about 3,000 obtained from a residual petroleum oil, and in the range of about 0.001 to 2 wt. of an ethylene backbone pour point depressant which has a molecular weight in the range of about 500 to 50,000 and is selected from the group consisting of: l. branched polyethylene, 2. ethylene polymer chlorinated to contain about 1 to 30 wt. chlorine, and 3. copolymers of 3 to 40 molar proportions of ethylene with a C to C alpha monoolefin, or a mono-ethylenically unsaturated monoor dialkyl ester having about 1 to 16 carbon atoms in said alkyl groups, wherein the relative ratio of said hydrogenated alkyl aromatic to said ethylene backbone pour point depressant is in the range of about 0.5 to 10 parts by weight of said hydrogenated alkyl aromatic per part by weight of said ethylene backbone pour point depressant,

and wherein said combination of said hydrogenated alkyl aromatic and said ethylene backbone pour point depressant shows synergy in improving the flow properties of said oil.

3. A distillate fuel oil according to claim 2, wherein said hydrogenated alkyl aromatic is hydrogenated waxnaphthalene, and said ethylene backbone pour point depressant is a copolymer of 4 to 20 molar proportions of ethylene with a molar proportion of unsaturated alkyl ester.

4. A fuel oil according to claim 3, wherein said unsaturated ester is a vinyl ester of a C to C fatty acid.

5. A distillate fuel oil according to claim 4, wherein said copolymer is a copolymer of 4 to 20 molar proportions of ethylene per molar proportion of vinyl acetate, and wherein said copolymer has a molecular weight in the range of about 1000 to 5,000.

6. A distillate fuel oil according to claim 2, wherein said hydrogenated alkyl aromatic is said hydrogenated alkyl aromatic fraction of said amorphous normally solid wax, which has a molecular weight in the range of about 600 to about 1,500 and is essentially free of normal paraffinic hydrocarbon, and said ethylene backbone pour point depressant is a copolymer of ethylene and said unsaturated alkyl ester.

7. A distillate fuel oil according to claim 6, wherein said copolymer is a copolymer of 4 to 20 molar proportions of ethylene per molar proportion of vinyl acetate, and said copolymer has a molecular weight of about 1,000 to 5,000.

8. An additive concentrate, useful for treating fuel oils to improve the flow properties thereof, comprising an oil solution of a mixture of 3 to 60 wt. ofa hydrogenated alkyl aromatic selected from the group consisting of:

a. hydrogenated wax naphthalene pour point depressant which is the Friedel-Crafts condensation product of wax having a melting point of about 100 to 200F. chlorinated to about 5 to 25 wt. chlorine and condensed with naphthalene in a relative weight ratio of about 5 to 15 parts of chlorinated wax per part of said aromatic, and

b. a hydrogenated alkyl aromatic fraction of an amorphous normally solid wax having a molecular weight in the range of about 600 to about 3,000 obtained from a residual petroleum oil,

and an ethylene backbone pour point depressant having a molecular weight of about 500 to 50,000 and selected from the group consisting of:

l. branched polyethylene,

2. ethylene polymer chlorinated to contain about 1 to 30 wt. chlorine, and

3. copolymers of 3 to 40 molar proportions of ethylene with a C to C alpha monoolefin, or a mono-ethylenically unsaturated monoor dialkyl ester having about 1 to 16 carbon atoms in said alkyl groups,

and wherein the relative ratio of said hydrogenated alkyl material to said ethylene backbone pour point depressant is in the range of about 0.5 to 10 parts by weight of said hydrogenated alkyl aromatic per part by weight of said ethylene backbone pour point depressant.

9. A concentrate according to claim 8, wherein said hydrogenated alkyl aromatic is said hydrogenated wax naphthalene pour point depressant, wherein said ethylene backbone pour point depressant is a copolymer of 4 to 20 molar proportions of ethylene with a molar proportion of vinyl acetate, and wherein said copolymer has a molecular weight in the range of about 1,000 to 5,000.

10. A concentrate according to claim 9, wherein said hydrogenated alkyl aromatic is said hydrogenated alkyl aromatic fraction of an amorphous normally solid wax, and wherein said ethylene backbone pour point depressant is a copolymer of 4 to 20 molar proportions of ethylene with a molar proportion of vinyl acetate and wherein said copolymer has a molecular weight in the range of about 1,000 to 5,000. 

1. A DISTILLATE PETROLEUM FUEL OIL HAVING AT LEAST A MAJOR PROPORTION BOILING IN THE RANGE OF ABOUT 250* TO 700*F., IMPROVED IN ITS FLOW PROPERTIES BY 0.01 TO 3 WT. % OF A FLOW IMPROVING HYDROGENATED ALKYL AROMATIC FRACTION OF AN AMORPHOUS NORMALLY SOLID WAX HAVING A METLING POINT IN THE RANGE OF ABOUT 80* TO 200*F. AND A MOLECULAR WEIGHT IN THE RANGE OF ABOUT 600 TO ABOUT 3,00 ABRAINED FROM A RESIDUAL PETROLEUM OIL.
 2. ethylene polymer chlorinated to contain about 1 to 30 wt. % chlorine, and
 2. A distillate petroleum fuel oil having at least a major proportion boiling in the range of about 250* to 700*F., improved in its flow properties by containing in the range of about 0.01 to 3 wt. % of a hydrogenated alkyl aromatic selected from the group consisting of: a. hydrogenated wax aromatic pour point depressant which is the Friedel-Crafts condensation product of wax having a melting point of about 100* to 200*F. chlorinated to about 5 to 25 wt. % chlorine and condensed with an aromatic in a relative weight ratio of about 5 to 15 parts of chlorinated wax per part of said aromatic, and b. a hydrogenated alkyl aromatic fraction of an amorphous normally solid wax having a melting point in tHe range of about 80* to 200*F. and a molecular weight in the range of about 600 to about 3,000 obtained from a residual petroleum oil, and in the range of about 0.001 to 2 wt. % of an ethylene backbone pour point depressant which has a molecular weight in the range of about 500 to 50,000 and is selected from the group consisting of:
 2. ethylene polymer chlorinated to contain about 1 to 30 wt. % chlorine, and
 3. copolymers of 3 to 40 molar proportions of ethylene with a C3 to C16 alpha monoolefin, or a mono-ethylenically unsaturated mono- or dialkyl ester having about 1 to 16 carbon atoms in said alkyl groups, and wherein the relative ratio of Said hydrogenated alkyl material to said ethylene backbone pour point depressant is in the range of about 0.5 to 10 parts by weight of said hydrogenated alkyl aromatic per part by weight of said ethylene backbone pour point depressant.
 3. A distillate fuel oil according to claim 2, wherein said hydrogenated alkyl aromatic is hydrogenated wax-naphthalene, and said ethylene backbone pour point depressant is a copolymer of 4 to 20 molar proportions of ethylene with a molar proportion of unsaturated alkyl ester.
 3. copolymers of 3 to 40 molar proportions of ethylene with a C3 to C16 alpha monoolefin, or a mono-ethylenically unsaturated mono- or dialkyl ester having about 1 to 16 carbon atoms in said alkyl groups, wherein the relative ratio of said hydrogenated alkyl aromatic to said ethylene backbone pour point depressant is in the range of about 0.5 to 10 parts by weight of said hydrogenated alkyl aromatic per part by weight of said ethylene backbone pour point depressant, and wherein said combination of said hydrogenated alkyl aromatic and said ethylene backbone pour point depressant shows synergy in improving the flow properties of said oil.
 4. A fuel oil according to claim 3, wherein said unsaturated ester is a vinyl ester of a C2 to C5 fatty acid.
 5. A distillate fuel oil according to claim 4, wherein said copolymer is a copolymer of 4 to 20 molar proportions of ethylene per molar proportion of vinyl acetate, and wherein said copolymer has a molecular weight in the range of about 1000 to 5,000.
 6. A distillate fuel oil according to claim 2, wherein said hydrogenated alkyl aromatic is said hydrogenated alkyl aromatic fraction of said amorphous normally solid wax, which has a molecular weight in the range of about 600 to about 1,500 and is essentially free of normal paraffinic hydrocarbon, and said ethylene backbone pour point depressant is a copolymer of ethylene and said unsaturated alkyl ester.
 7. A distillate fuel oil according to claim 6, wherein said copolymer is a copolymer of 4 to 20 molar proportions of ethylene per molar proportion of vinyl acetate, and said copolymer has a molecular weight of about 1,000 to 5,000.
 8. An additive concentrate, useful for treating fuel oils to improve the flow properties thereof, comprising an oil solution of a mixture of 3 to 60 wt. % of a hydrogenated alkyl aromatic selected from the group consisting of: a. hydrogenated wax naphthalene pour point depressant which is the Friedel-Crafts condensation product of wax having a melting point of about 100* to 200*F. chlorinated to about 5 to 25 wt. % chlorine and condensed with naphthalene in a relative weight ratio of about 5 to 15 parts of chlorinated wax per part of said aromatic, and b. a hydrogenated alkyl aromatic fraction of an amorphous normally solid wax having a molecular weight in the range of about 600 to about 3,000 obtained from a residual petroleum oil, and an ethylene backbone pour point depressant having a molecular weight of about 500 to 50,000 and selected from the group consisting of:
 9. A concentrate according to claim 8, wherein said hydrogenated alkyl aromatic is said hydrogenated wax naphthalene pour point depressant, wherein said ethylene backbone pour point depressant is a copolymer of 4 to 20 molar proportions of ethylene with a molar proportion of vinyl acetate, and wherein said copolymer has a molecular weight in the range of about 1,000 to 5,000.
 10. A concentrate according to claim 9, wherein said hydrogenated alkyl aromatic is said hydrogenated alkyl aromatic fraction of an amorphous normally solid wax, and wherein said ethylene backbone pour point depressant is a copolymer of 4 to 20 molar proportions of ethylene with a molar proportion of vinyl acetate and wherein said copolymer has a molecular weight in the range of about 1,000 to 5,000. 